Green Algae Biomass Cultivation, Harvesting and Genetic Modifications for Enhanced Cellular Lipids

Abstract

Petroleum based fuels are accepted as unsustainable because of depleting supplies and cause of accumulation of CO2 in the environment. Out of the other sources of energy, which are generally considered to be alternative source of energy, algae based biofuel is comparatively new idea. The oil content of various microalgae is up to 80% of their dry biomass. Photosynthesis based biofuel production summarize energy production with biological carbon dioxide fixation. Ideally they are carbon neutral, and they minimize emission of greenhouse gases. Microalgae are the group of microorganisms, which contains a huge amount of triacylglycerol inside the cellular organization, which produces FAME (fatty acid methyl esters) via trans-esterification process. They also require a least land area relative to other biofuel crops. They are highly promising biofuel source. The production of biofuel from microalgae is a complex process. It comprises microalgae cultivation in a low cost nutrient medium, harvesting of cells from cultivation medium. Heavy investment in microalgae cultivation, harvesting and processing require very high productivities, greatly exceeding those of terrestrial crops. The maximum achievable photosynthetic efficiency, and thus biomass productivity, of microalgae cultures has been controversial for nearly a century and is still unresolved, as reflected in recent peer reviewed literature. Actual and projected microalgae biomass productivities, based on commercial production, outdoor experimental work, laboratory data and theoretical projections, range from about 20 to over 200 mt dry organic matter/hectare-year. Methods of genetic modifications of algal strains to be more efficient in the production of biofuels are still in their infancy. One of the main goals of genetic engineering in this relation is to improve algal strains so that they can create a source of alternative energy that is more environmentally friendly and sustainable for the accumulation of lipid content in their cells which can be utilized as source of biodiesel.